Effect of Gd Addition Amount on Microstructure and Mechanical Properties of Mg-Gd Alloy Fabricated by Wire Arc Addictive Manufacturing

Mg-Gd alloys with Gd mass fraction of 2%,3%,10% were prepared by tungsten inert gas (TIG) arc additive manufacturing technique. The effect of Gd content on the microstructure and mechanical properties of Mg-Gd alloys was studied. The results show that the microstructure of Mg-Gd alloys with different Gd content were all mainly composed of magnesium matrix and the second phase Mg₅Gd. With the increase of Gd content, the number and size of the second phase Mg₅Gd distributed along the grain boundary increased, the shape changed from round particles to long strips; the Mg grains changed from columnar grains to equiaxed grains. The number and size of pores in the alloy decreased, and the grain size decreased first and then increased, reaching the minimum with 3% Gd. With the increase of gadolinium content, the strength of the alloy increased and the elongation after fracture decreased. The fracture methods were all ductile fracture.